Linden Olson
Linden Olson

It’s been one of the coldest winters in Minnesota in more than 30 years and winter isn’t over yet.  While relaxing in our Arizona mountain cabin for a few weeks this winter I began thinking about some of the changes in the pork industry over the past 60 years, especially those related to raising pigs in the winter. 

Keeping Pigs Warm
One of my first memories about pigs was going down to breakfast and seeing the occasional bushel basket of newborn pigs sitting in the kitchen by the wood-burning stove, getting dried off and warmed up before being taken out to the farrowing barn and put in a pen with their mother.  In the 1940’s in the northern corn-belt there were fewer litters born in the winter than in other months.  Farmers who farrowed sows from November to March made many journeys from a warm bed in the middle of the night to check on sows ready to farrow in the  uninsulated, straw-bedded barns heated by wood or/and cob stoves.  There were always a few fires somewhere in those northern barns started by sparks getting into the straw or landing on the wood shingle roofs.  It was not until the late 1940’s that propane heaters were introduced to heat farrowing barns.  It was a big event when our farm got a Reznor propane heater for the farrowing barn.  That heater lasted until the late 1970’s – more than 30 years!     

Up to the 1960s most farrowing barns had 8’ x 8’ pens for sows to farrow in.  There would be one or two corners boarded off with a heat lamp to draw pigs to a warm sleeping area that would later be used as a creep to get the pigs eating dry feed before being weaned. The sows would be let out of the pens twice a day, often outside, for feed and water and hopefully to dung so the pens wouldn’t have to be cleaned too often. While the sows were out eating the pens would be cleaned and new bedding added as necessary. Death losses were quite high from baby pigs being laid on in these pens.     

Injectable Iron
Today injectable iron is the gold standard for preventing iron deficiency anemia in baby pigs. For pasture-farrowed pigs, anemia was not a concern because the pigs would eat enough dirt to get the necessary iron. Prior to the early 1960s when iron dextran (trade named Armidextran) became commercially available other ways of preventing anemia had to be used to prevent anemia in piglets born inside during the winter months. 

The first and oldest method was to get dirt from a field and put some in the creep area where the pigs could eat it. In the winter north of I-80 that meant taking a shovel, pick ax, and pail out into a frozen field, shoveling off the snow and using the pick ax to knock loose a few clumps of dirt, putting them in the pail and taking it back to the farrowing barn to thaw for a day or two before giving some to the pigs.  A second method was to catch each pig 2 or 3 times a week and orally dose each with a paste of iron sulfate.  A third way was to swab the sow’s udder once a day with the iron sulfate solution and as the pigs nursed they would get the necessary iron. 

Some of the research on injectable iron was done at the University of Minnesota in the late 1950s. As an undergrad there during those years, one of the part-time jobs I had was chief bottle washer of the vials used to collect the blood from the pigs used in the research trials. The research compared hemoglobin levels from pigs getting the injectable iron to pigs nursing sows whose udders had been swabbed with an iron sulfate solution. Blood was collected weekly from each pig for five weeks, the normal weaning age at that time. 

The early results showed that two injections of the iron dextran, one shortly after birth and another at 3 weeks of age, were necessary to prevent anemia until pigs were weaned at five weeks. Both methods prevented anemia but the labor savings of injectable iron made it the preferred way and now is used by nearly all pork producers today. There were no computers in the late 50s, so all the data was crunched on hand-cranked calculators.

A lot of changes were made during my 60-plus years of raising hogs – many of them made hog chores during the long winters a whole lot easier and more enjoyable. I find that a lot of individuals involved in pork production are not aware of the changes that make their work simpler and easier, especially during extreme winter weather like many areas of the country are experiencing right now.